#include<iostream>
#include<vector>
#include<cmath>
using namespace std;
int dp(int n)
{
    vector<int> dp(n+1);
    if(n<2)
        return 0;
    dp[0] = 0;
    dp[1] = 0;
    dp[2] = 1;
    for(int i=3;i<=n;i++)
    {
        int maxNum = 0;
        for(int j=1;j<=i;j++)
        {
            maxNum = max(j*(i-j),max(j*dp[i-j],maxNum));
        }
        dp[i] = maxNum;
    }
    return dp[n];
}
int main()
{
    cout<<"enter a number:"<<endl;
    int n;
    cin>>n;
    cout<<"the result is:"<<dp(n)<<endl;
    return 0;
}